Using "Eye-Fi Mobi" card

Are there experienced "Eye-Fi" folks out there?
I am thinking of trying out an "Eye-Fi Mobi" card this June to send photos from Italy to iCloud from my iPhone. As I understand the process, photos can be transferred from my Canon G-15 to my iPhone. What to do then is the question. Do I go to some spot with WiFi and upload photos from iPhone to iCloud? Can my family then download the photos from iCloud? Will the photos diminish in quality in the Cloud? Is the whole thing going to cost an arm and a leg in "data" fees? Or does the fact that I'm using Wi Fi avoid the fees? In the past I've just carried several cards and brought all the photos back to load and edit on the computer. Thanks for any advice, hints, warnings, etc.